*{margin: 0;padding:0; }
ul{list-style: none;}
.banner{width: 600px;height: 300px;border: 2px solid #ccc;margin: 100px auto;position: relative;overflow: hidden;}
.img{position: absolute;top: 0;left: 0}
.img li{float: left;}
.num{position: absolute;bottom: 10px;width: 100%;text-align: center;font-size: 0;}
.num li{width: 10px;height: 10px;background:rgba(0,0,0,0.5);display: block;border-radius: 100%;display: inline-block;margin: 0 5px;cursor: pointer;}
.btn{display: none;}
.btn span{display: block;width: 50px;height: 100px;background: rgba(0,0,0,0.6);color: #fff;font-size: 40px;line-height: 100px;text-align: center;cursor:pointer;}
.btn .prev{position: absolute;left: 0;top: 50%;margin-top: -50px;}
.btn .next{position: absolute;right: 0;top: 50%;margin-top: -50px;}
.num .active{background-color: #fff;}